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19 seconds at top speed

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Are you sure it's a fcr?Keihin never made a 40 that I'm aware of,usually 33,35,37,39 and 41mm.

Should be able to flow fine even at wot.Check to make sure gas tank is venting.

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At 1 point or another , both the CRF250R and 450R have used the FCR-MX 40mm. It is a more refined carburetor than what the other OEM's and aftermarket get. 1 benefit is they redesigned the accelerator pump actuator, eliminating the need for the o-ring mod.

 

Take a picture of the accelerator pump actuator so I can see what you have.

 

If you use the E model petcock then you can also use the E fuel line and it fits like it came from the factory that way.

 

Also, you need to take the carb back off and look at your float level and see what size leak jet you have( if it is a Honda 40mm) If it has a leak jet you'll need to use something smaller than the stock 70. I remember reading that the Z400 guy were using 55 leak jets.

 

 

 

 

 

 

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Yes the carb is the same one as on my CRF450R, no O ring mod needed. The rapter petcock is brand new and only noticed the problem after installing it. Its almost as hard to get the tank on as the stock petcock is ,it interferes with the hot start boot on the FCR40MX .I got a hot start lever kit from Magura and made a bracket to mount it on the clutch perch .I will also check the leak jet ,thank you !

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You won't really need the hot start on the Z , maybe once in a great while after a spill . I plugged my hot start with a Yamaha YFZ unit that's on their fcr's . I also then used the hot start lever and cable (crf250) and put the choke plunger on it with the billet nut and now have my choke up on the bars , I'll never go back to the hidden knob on the carb that I could barely use because it hit the petcock right as it got to full choke . Did it on my 3 FCR biikes .

DSCN1570_zpsgeiu8y1b.jpg

 

My guess as to why your running out of gas is because your fuel line is kinked off and limiting flow . That crappy setup with the outlet coming out right toward the carb is just asking for trouble so I went with a downward outlet petcock and kept my hose nice and free . The E petcock is probably the best solution .

 

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Edited by jjktmrider
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Yes I, was just looking for a little more clearance for the FCR40MX hot start boot .if the E petcock doesn't have any more clearance than stock , I  could put it back on today . Has anyone's K n N filter started  deforming under the clamp pressure? 

20170218_141311.jpg

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Yes I, was just looking for a little more clearance for the FCR40MX hot start boot .if the E petcock doesn't have any more clearance than stock , I  could put it back on today . Has anyone's K n N filter started  deforming under the clamp pressure? 
20170218_141311.thumb.jpg.0da4adc35f5919235dd63c99e5702ca7.jpg

Throw that over priced pos away. Use a good quality foam filter.
I have a KN I bought, put on, rode around the block and took off. If you send me a brand new Uni or Twin air filter I'll send you this one. That applies to anyone interested.1494787632845.jpeg
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125 ,but i just installed a 146cc big bore kit last Friday with a new carb. You think the 55 leak will be good on MY DRZ  setup?

Nice. I have a 140 with the 146 hi compression head gasket in a CRF70, she rips.

Anyway, 55 is what I read, I haven't tired it. I bought and was going to install a 40 on my bike just to see if there was a difference but the opportunity came to sell for a little profit and I took it. The aftermarket FCR's don't have a leak jet, the DRZ can handle the full squirt without bogging like the smaller bore bikes but since you have the ability to dial it in perfect you might as well take advantage of it.

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